Heating system



June 2, 1942.

c. l. MURDOCK 2,284,674

HEATING SYSTEM Filed Dec. 16, 1937 2 Sheets-Sheet 1 ATTORNEYS 2 Sheets-Sheet 2 NVENTOR Y fiz PM.

ATTORNEYS C. l. MURDOCK HEATING SYSTEM Filed Dec. 16, 1937 June 2, 1942.

Patented June 2,1942

UNITED STATES .PATE-NT OFFICE HEATING srs'rsu Charles I. Murdock, Perry, N. Y., assignor of onehalf to John B. Mollnow, Perry, N. Y.

Application December 1 6, 1937, Serial No. 180,183

- o 22 Claims. This invention relates to heating systems of the type in which heated air is circulated through a room or rooms and a heating unit in succession, and is particularly useful in that type of heating system in which the air may also be conditioned. Heating units have recently come into extensive use of the type in which heat is applied intermittently under the control of a thermostat disposed either in a room being heated or in a position in which it is directly responsive to the ternperature of the room. Due to such intermittent operation of the heater, that is, with respect to the intermittent supply of heat thereto, it follows that the temperature of the air delivered by the heating unit will be relatively high while the heat is being supplied to the unit and for a short time after the supply of heat is discontinued and while,

the heating unit is cooling oil, and relatively lower while no heat is being supplied to the unit and after the unit has cooled.

If the difference in densities between the 'heated and normal air is relied on to-cause circulation of the air through the heating-unit, it follows that when no heat is supplied to the unit 10 that as the air in a room cools, the circ furnace are not supplied with air when the blower is stopped.

flculty by circulating the air .through the heat- 5 ing unit and a room or rooms continuously by a motors for the blower, and special thermostats placed at various positions to control the speeds, but such controls have not been entirely satisfactory.

An object of this invention is to generally improve heating systems of this type, and provides a heating unit which will maintain the most desirable atmospheric conditions in said room or rooms at all times, and whichv will be relatively simple, compact, effective, eflicient and inexpenit will cause no appreciable movement of air sive.

through the room, with the result that the air in the room has a tendency to stratify into horizontal layers or zones of diflerent temperatures. The coldest air settles to the bottom of the room, and the hot air rises to the top, with strata of ,intermediatetemperatures between the two, so

that a thermostat on the wall of the room intermediate the floor and ceiling. will indicate a temperature which corresponds to the temperature practice the blower and burner were operated simultaneously. This method corrected the stratiflcation while the blower was in opera tion.

When the blower stopped, the personal comfort in the room was less than withthe heating system operating'on a'gravity basis. The common application today on-the forced air or conditioned air system is to start the blower at about 115 at the bonnet of the heater and stop the same at 125'. This method does not function properly, for e short pipes feed warm air to the rooms where connected, and the rooms far from the Another object of the invention is to provide an improved heating unit and heating method for systems of this type, with which stratification of the air in any room into. different horizontal 3 zones of different temperatures may be effectively prevented, and the movement of the air in the room socontrolled .as to prevent objectionable drafts of relatively cool air at all times, and yet with which the wer consum tion f or atin of the air in that strata but not the strata at the as p M e g the circulation of air in the room will be a mini .mum .undenall operating conditions.

Another object of the invention is to provide an improved. and compact heating unit, with 40 which maximum efilciency of heat transfer will be obtained in a simple and effective manner.

Another object of the invention is to provide improved and eifective means and methods for adding moisture to the air being circul ted through any room, with which waste of wa r will be reduced to a minimum, and vaporization accomplished eiiiciently in accordance with the activity of the heater.

Various other objects and advantages will be apparent from the following description of an embodiment of the invention, and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings Fig. 1 is a sectional elevation through a heat- Attempts have been made to remedy this air- 1 ing unit constructed in accordance with this inventlon;

- Fig. 2 is a sectional elevation through a part of the same, the section being taken approximately along the line 2-2 of Fig. l, with portions broken away to show interior details;

Fig. 3 is a front elevation,'partly in section,

of the same, with the section taken approximately along the line 3-4 of Fig. l:

Fig. 4' is an opposite, rear elevation of the same, partly'in section, and with the section taken approximately along the, line H l; and

of Fig.

asses but is preferably-of the type in which the heat is lll 'plied only intermittently under a suitable control. In the example illustrated, the heatingmedlum is supplied to the section 200, at the bottom portion thereof, from a flame compartment 22 of a suitable burner 24.

This burner may operate with any desired fuel. but gas and oil burners are the most commonly employed in the intermittent type of heating unit. In the drawing on oil atomizing and air mixing or fuel supply unit 25 is illustrated conventionally and arrangedto supply a combusti- -ble mixture of air and fuel to the flame com- Fig. 5 is a sectional elevation through a portion of'the same, with the section taken imately along the line 5-5 of Fig. l.

Inthe illustrated embodiment of the invenapprox-,-

tion, the improved heating unit includes a cab- *inet llof any suitable or desired shape into one zone of which the cold air return conduit ll opens and into another zone of which a hot air supply conduit I2 opens. The conduits II and livered to conduit I 2 is above approximately 80 F" blower I3 is operated continuously and at an approximately constant. speed, in any suitable manner, such as by a motor II which is connected to the rotor I311 of the blower It in any suitable manner such as by a driving belt IS. The blower is illustrated as of the centrifugal type, which is,preferred, butfobviously other types of air circulating devices may be used within the broader concept of the'invention. v v The blower i3 is preferably and conveniently disposed within the cabinet I I) at one side of a partition it which passes across the interior of the cabinet ill, .but disposed between the conduits II and i2. This partition I6 has an aperture or opening ll adjacent its lower end by which air may pass from one side of the partition to the other in its travel between the conduits II and I2. The blower l3 at its intake side opens into the compartment i8 of the cabinet at the side of the partition is into which thecold air conduit ll opens. At its discharge side the blower I: is connected to and fills the aperture or opening ll oi the partition it so that the blower draws air from the compartment l8 and delivers it under pressure through the opening I! into the compartment l9 at the opposite side of the partition l6, and into which compartment IS the hot air conduit l2 opens. The conduits II and I2 conveniently upper'part thereof. Within the cabinet 'I provide a heat exchange device 20," one section 200 of which is disposed in the compartment l9 and. another section 201; of which is dispos d in the compartment It, the sections a and 20b being connected'in series to one another by a pair of conduits 2| which pass through the partition IS. A fine discharge pipe- 22 connects the interior of the section 20b with the exterior of the-cabinet,.and as usual connects to a chimney or other flue discharge device. A heating medium is su lied to the section 20a of the exchange device inany suitable manner,

partm'ent 23 where it isignited and burned. The burning gases rise and pass through the section 20a which may be called the combustion chamber and thence pass through the pipes or conduits 2| into the section zoo and thence through the exhaust flue 22. The unit 25 is operated intermittently in any suitable manner, but a simple intermittent control therefor is illustrated dia grammatically in Fig. l. Inaccordance with such control a thermostat 26-, which may be conveniently disposed in the room to be heated, is included in a, low voltage. electric circuit 21 which also includes in series therein the secondary winding of a transformer 28 and the winding of an electromagnetic switch or relay 29., The relay 29, through'its contact mechanism, controls a commercial line circuit represented by line wires LI, L2 running to the mixing unit 25, the switch device 30 being in series in the circuit to the unit 25. The primary of the transformer 28 is connected also to the line wires LI and L2. The lines wires'Ll and L2 may represent a standard commercial electric lighting circuit.

transformer 28 supplies a low voltage current of approximately 6 to 12 volts to the thermostatic circuit 21. Thus when-the thermostat 26 closes its circuit, relay 29 will be energized and will close the circuit-to the mixing unit 25 and cause the delivery of a supply of heat to the heat exchange device in the cabinet.

When the temperature in the room reaches the desired maximum, opens its circuit 21 cause a deenergization of the relay 29, an opening of thecontact mecha-' nism 30, and a shutting down of the mixing unit 25, with a resultant cutting off of the delivery of heat to the heat exchange device. Inasmuch as the thermostatic control of the operation of any such mixing-unit 25 is well known in the art by itself, and per se is'no part of the present invention; such control has been illustrated only diagrammatically, and it will be understood that any suitable thermostatic control, by which the mixing or fuel supply unit 25 is operated intermittently as needed to maintain a desired ten perature in the room, may be employed. The

open into the cabinet at the v fuel andair are discharged by the unit 25 into the flame compartment 23 which is lined with refactory material or any other suitable lining material, and this compartment 23 opens up wardly into the lower part of the-section 20a which forms the combustion chamber where the combustion of the fuel is completed. 'The gases of combustion then pass through the pipes 2| and the heat exchange section 20b discharge pipe 22.

The section 2lib which may be termed a secondary heat exchange element, may be of any suitable design, but is preferably-of the type having headers 3| and 32 which are-connected by a plurality of thin fiues 33, slightly spaced from v I one another, so that the air to be heated may pass The" e thermostatic switch 26 to the flue downwardly between the flues for a heat exchange with the gases of combustion. The flues 7 83 are preferably exteriorly convex so as to proextending directly toward the opening into the hot air conduit I! like the peak of house roof.

In one or both of the conduits ll or I! I place means'for partially and materially restricting, but not fully obstructing, the flow of air through the cabinet I. Preferably a damper 35 is placed in. the cold air conduit II, and a damper 36 is placed in the hot air conduit l2. Each damper may be of the butterfly type fitting loosely in its conduit and having sumcient clearance between its periphery and the conduit walls so that the conduit cannot be fully closed when the damper is in closed position. For example, a clearance of at least one-half inch may be provided between the periphery of each damper and the adjacent walls of the conduit in which it is placed. The dampers are both fixed on a shaft 31 so as upper part of compartment l8, so as to screen out dust fromvthe relatively cold air entering the compartment l8 from the cold air conduit II, but inasmuch as such filters are well known in the air conditioning art, they have been illustrated only diagrammatically or conventionally, and it will be understood that any of the usual types, of such filters or screens may be employed. They are preferably made in sections disposed at an angle to one another, as shown in Fig. 1.

A removable cover 45 may be applied over the unit 25, and this cover may have air admission louvres as. A safety control passage 41 and a to oscillate therewith, and the shaft 3'! extends between and through both of the conduits and is rotatably supported by the conduit walls. The shalt 3l-is controlled or operated in any suitable manner, either directly or by remote control,' from a thermally responsl-ye device 38 that is disposed in a position where it is directly re- LDLIlSlVG to the temperature of the air delivered by the cabinet Hi to the hot air conduit 12. This thermally responsive device 38 may advantageously be disposed within the hotair conduit [2, and operatively and directly connected or coupled in any desired manner to the damper shaft 31 The thermally responsive device 38 may, for example, be a bimetallic spiral device or helix, one end of which is anchored to the shaft 31 which extends through the conduit 12, and the other end of which bimetallic element is anchored in any suitable manner. An example of such an element is shown in U. 8. Patent No. 1,989,278 of January 29, 1935. In the present example the thermal element is anchored .to a stud 39 which is clamped to a plate 4|] provided on a side of the conduit l2. The plate 40 is releasably mounted on the conduit in any suitable manner such as by screws 4i, and the stud 39 passes through a slot 42 in the plate 40. The

slot '42 is arcuate with its center of curvature service door 48 may be provided on one side of the heat exchange section 20a and a'ccessib when cover 45 is removed. Within the chamber I8 I preferably provide a radiation shield 48 between the section 20a of the housing for the combustion chamber and the outer wall of the cabinet, and spaced from both. The upper part of the side walls of shield 48 converge towards the opening into the hot air conduit l2, so that the air ascending between the shield and the section 20a will wipe along the tapered or peak shaped top of the housing or section 2841 as well as the shield and be discharged directly towards the opening into the conduit l2. Since the radiation shield is spaced from the outer walls of the cabinet Ill, air may pass along all of its faces. The shield absorbs radiant heat from the heat exchange section 20a, and the air moving along the shield is directly heated by this radiant heat that has been absorbed by the shield. The temperature of the outside walls of the cabinet is thus kept low and a more effective and eflicient heat exchange between the gases of combustion and the air passing through the cabinet is obtained. While one devices are in common use in the air conditioning art, and my invention in its broader concept comprehends the utilization of any of those ther flue 2| may be provided between the sections 20a the "air delivered to the room ;A, I provide a spraying device 49a at any suitable point within the chamber l8, so as to discharge a fine spray of water into'the air of the chamber l8 well above the ,heat exchange element 20b. Thus, the

water is sprayed into the descending current of air} and the mixture of air and water is carried over and through the heat exchange element 20b where the heat vaporizes any water mechanically entrained in the air. The water is supplied to the spray device 49a by apipe. 50 which extends into the chamber between the front wall of the cabinet I8 and the cover 45. where it is connected to an electrically controlled valve 5| of .any suitable construction. Water is supplied to the valve 51 by a pipe 52 from any suitable source of water under pressure. Wire 58 connects one side of the valve 5| to the line wire L2. Mounted upon the end of the damper shaft 81 which extends through the plate 48 are a pair of mercury tube switches 54 and 55. These mercury switches are very common in the art, and one is shown by way of example in U. S. Patent No. 1,989,278, issued January 29, 1935. A wire 58 leads from the line wire Ll to one contact of each of these mercury switches. The other contact of the switch 54 is connected by a wire 54a to the other side of the valve 5|. The tubeof the mercuryswitch 54 is so positioned on the damper shaft 81 that it closes the circuit between the line wires,

and through-the valve 5|. whenever the t rmostatic device 88 operates the dampers 85 an 88 to any substantial extent away from fully open positions in the conduits II and i2, and keeps the circuit closed until the dampers return to approximately wide open positions.

pipe 58 and thence be discharged through the spray device 48a into the air descending in the chamber l8.

As soon as-the damper 95 moves to any appre- ,ciab,le extent away from its open position, in a full opening of the dampers is preferably around 125 to 130 F., but the dampers start to open when the temperature exceeds a particular temperature, such as about 80 F. Thedampers door 48 is forced slidingly and snugly into the closing direction, the mercury switch 54 will close the circuit to the valve device 5| and cause operation ofthe latter to cut off the supply of water to the spray device 49a. While the mercury switch 54 may be so positioned on the damper shaft, and the valve 5| so designed. that the valve 5| is operated to admit water to the spray device 49a when the circuit is closed, and

' causes-a cutting oil of the water by an opening of the circuit when the damper moves away from fully open position, the arrangement illustrated.

provides for the closing of the circuit to cut oil the water spray when the dampers start to close. Thus water will be sprayed into the air only while the dampers are in fully opened positions, and the water supply will be cut oil as soon as the dampers start to close. The other mercury switch 55 is connected, at the side opposite the connection to. the common wire 58, by a wire 55a to one connection of the,motor l4, and the .other connection of the motor I4 is conntcted by a wire 55b to the line wire L2.

The switch 55 is so positioned on thedamper shaft that it completes a circuit to the motor l4 as soon as the dampers begin to open from their straight across or relatively closed positions, and keeps the circuit closed'as the dampers continue to open and while they are in fully open position.

Ihe thermal device 38 is so constructed as to cause a start of the opening movement of the. 1

- dampers. whenever. the temperature rises above approximately 80 F. Thus whenthe dampers are fully closed, that is, in a position straight service passage 48a and held frictionally therein .by an annular packing ring 48b of fire resisting material such as asbestos wicking, and is connected by a chain 58 to a removable switch plug 59 of a. switch 68 which is included in series with the burner device or unit 25. This friction normally holds the door 48 in closed position in passage 48a. In the event of an explosion in the combustion chamber, the door 48 will be blown outwardly into the interior chamber of the cover and through chain 58 will pull plug 59 and blown outwardly by an explosion, the circuit to the burner 25 will be opened and the operation of the burner shut down automatically. Thisis av simple but eiiective safety feature.

. In order to insure maximum effectiveness in the flue passages 21, will be obliged to travel well across the ducts, the switch 55 will open the circult of the motor l4 and shut down the blower which will be whenever the temperature of the air being delivered by the furnace is approximat'ely 80 F. or lower, but as soon as the furnace starts delivering heated air above 80 F., the

. dampers will start to open and the blower will be started so as to forcibly circulate air through the chambers and l9 in succession. a

The damper 3,5 in the hot air duct l2 is-provided with .a notch 51 which clears the thermostatic device 38 in all of'the angular positions of the damper 38, and thus there will always be a portion of anyair circulating through the duct l2, moving through and around the thermal. device 38,v thus making the thermal device at all times directly responsive to the temperature of the air delivered to the jconduit l2, whether or below that for which the thermostat 26 is set,

up into the upper par of the combustion cham-' her and then descend? through the slots 5| into the passages 2|, in order .to reach the other'heat.

exchange section 20b.

It is also advantageous to insure'that some of the air delivered by the blower i3 through the opening i'l into the chamber l9 will pass around all partsof the ,fire box 23, and for this purpose a baiile plate 62 (Fig. 1) may be positioned across the opening I! through which air is delivered by the blower l3. This baflle plate 62 extends horizontally across the opening I I and within the chamber i9 may be curved upwardlyv slightly, as shown. Baflles of this shape and type and positioned in this manner aid in insuring the delivery of some of the circulated air around the fire box 23 before it rises through the chamber I9 to the duct l2. The operation of the device should be clear from the foregoing description, but will be briefly /summarized. The conduits II and I2 are connected to diiferent zones of a room to be heated or air conditioned, or by branches to difierent rooms, as usual in this type of heater, and the thermostat 28 is set to maintain the desired temperature in the room. If the temperature falls the latter will close the circuit 21 and through' it and relay 29 will close a line circuit'from line wires Ll', L2 to the fuel supply unit 25. This unit open switch 68.- Thus whenever the door 48 is.

. will be at the bottom thereof, so that are away from approximately straight across or closed positions in the ducts. The blower, which is operated by the motor It, draws air from the room or rooms through the conduit I I into the' compartment is, where the air is partially heated by the outgoing flue gases in the section 20b, and then this partially heated air is iorced under blower motor is cut on, because this temperature or air in duct II will be reached only when there is so little temperature diiierence over outside temperatures that no objectionable stratification oil'air will occur. This eflects a saving in operating power costs when the outside temperature is mild and the forced circulation of air through the heater unit is unnecessary.

The reduction of. air flow through the cold air conduit, by the operation of the damper 35, to

approximately that which it is desired to pass through the cabinet, while the bumer is shut oi! and blower II is still operating, reduces the load pressure through the compartment l9, and delivered under"pressure through the hot air conduit II to the room or rooms to be heated. The

air of course is further heated in the compartment is by heat exchange with the hotter gases in the section Illa. Any dust in the air is removed in the filter screens N, and the air delivered into the compartment I9 by the blower e air receives some heat by radiation and conduction mm the flame compartment 23 as well as from the section 20a of the heat exchanger 20.

Wheneverthe temperature or the air delivered through the conduit I2 is above-say 80 F., the thermostatic device "will open the dampers 35 and 38, to increasing extents, with temperature increases, until fully open, so as to allow maximum air travelethrough the conduits n and I:

, and the cabinet I0, and aifter the temperature of the room or rooms has been brought to that for which the thermostat or thermal device 28 is set, the circuit 21 will be'opened, the relay 2! deenergized and the switch 30 opened, thus stopping the admission of iuel from the fuel I! continues to operate at the same constant speed, the circulation oi, airthrough the cabinet I. will continue, but owing to the fact that the supply of fuel to the combustion chamber has been cut oil,- the heat exchanger 20 will soon cool 01!, and transfer or heat to the air through the cabinet will decrease.

The continued operation oi'the-blower will maintain a circulation of air in the room so as to prevent stratification oi the air oithe room into zones of diiierent temperatures, but as the air delivered through the conduit l2 cools oii,

, such as below 130 F., the thermostatic device ll will tend to close the dampers I5 and I and paron the blower to a minimum, and consequently the motor ll will require a minimum oi. current to maintain the blower at a constant speed under such conditions. While the damper in the cold air conduit alone would regulate theamount of airpassing through the cabinet, I have found that the use of dampers in both-hot air and cold air conduits aids very materially in obtaining a very quiet operation, yet the load on the motor is kept to a minimum when the volume 0! air handled is reduced. 7,

It will be understood that various changes in the details and arrangements of parts which have been herein described and illustrated in order to explain the nature 01' the invention, may

be made bythose skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim as my invention:

1. An improved heating system of the type which heated air is circulated through a room or rooms, comprising a heating unit having a cold air return conduit leading from one part of said room or rooms and opening into said unit at one point, and a hot air supp y conduit openins out or theunit at another point and leading to another part of said room or rooms, a motor operated blower associated with said unit for cirsupply unit 25 to the burner. Since the blower Y culating relatively cold air from said room through said cold air return conduit to said unit and after a heat exchange in said unit delivering it to said hot air supply conduit for return to said 7 room, a tenfperaturc responsive device disposed tially and materially restrict, but not fully obstruct, flow or air through the conduit ll. Thus suilicient' air will be continuously circulated through the cabinet II and the room at all times,.

so as to prevent stratiiication of the air of the room, yet when the dampers are closed or partially closed the movement of the airwill be gentle enough so that occupants of the room will not he annoyed by objectionable drafts of relatively cool air, and some oivthe moving air in conduit II will pass through notch 51 in damper II where it will airect thermal device 38. By determining the closeness of fitting oi, the

- dampers 35 and 38 in the conduit I l ,the proportion 01' the air' allowed to flow at any time through the cabinet it when the damper is cloud vor nearly closed may be predetermined to some extent. when temperature of the air in duct l2 falls to. sa 80 F., the circuit to the in a position to be directly and immediately responsive to the temperature of the air in said unit which is delivered through said hot air supply'conduit, a damper in one 0! said conduits and controlled by said heat responsive device for operation into new restricting but not flow preventing position when the temperature of the air deliveredlby said unit falls below a selected temperature but above-normal room temperature, and for opening it through increasing extents as the temperature of the air delivered from the unit rises above. said selectedtemperature above normal room temperature, whereby whenever the temperature of the heated air delivered by the unit falls below a selected temperature, the flow oi'air through the unit automatically will be partially but not fully cut down in order that the stratiflcation, oi' the air in said room into diflerent horizontal zones oi diii'erent temperatures may be prevented and the movement 01' air in the room decreased to prevent objectionable drafts of relatively cool air,-

and means for keeping said motoroperated blower continuously running whenever said damper is materiallyaway from maximum restricting'position .-2. An improved heating system for an enclosure of the type in which heated air is circulated through said enclosure, comprising a heating unit having a cold air return conduit leading from one part of said enclosure and opening into said unit at one point, and a hot air supply conduit opening out of the unit at another point and leading to another part of said enclosure, a motor operated blower associated with said unit for circulating relatively cold air from said enclosure through said cold air return conduit to said unit and after a heat exchange in said unit delive'ring it to said hot air supply conduit for return to said enclosure, means including a device 1 directly responsive to the temperature ofthe air a position in which it partially but notfully re-' stricts air flow through said unit between said conduits whenever the temperature of the air delivered by said unit is below a selcted temperature but above normal roomtemperature, whereby objectionable drafts of relatively cool air and stratification of the air in an enclosure into difi'erent horizontal zones of diilerent temperatures may be prevented, and means for keeping said motor operated blower continuously running when the temperature of the air delivered by the hot air conduit is above a desired temperature thatis below said selected temperature.

3. An improved heating system for an enclosure comprising a heating unit having a cold air inlet conduit and a hot air outlet conduit opening into said unit at spaced zones thereof and connected to difierent parts of said enclosure, so

that air passing between said enclosure and conduits must pass through said unit, said unit containing means for imparting heat to the air v passing therethrough, means including a thermal device responsive to the temperature of the air in said enclosure for supplying heat to said.

unit intermittently as needed to maintain a desired temperature in said enclosure, a motor operated blower associated with said unit tor forcing air through said unit from said coldair conduit to said hot air conduit, a damper in said cold air conduit operable into and out of rooms, and comprising a heating unit, a cold air supply conduit connected to one part of said unit, a hot air delivery conduit connected to another part of said unit, a motor operated blower associated with said'unit and'conduits for torcing air through the unit from said cold air conduit to said hot air conduit, said unit having heat exchanging means therein for heating air passing therethrough, means for intermittently supplying heat to the heat exchanging means of said,

- unit, a 'da'mper'in each of said conduits operable between an open position in which it offers a minimum of resistance'to air flow between the conduits through the unit and a restricting position in which it partially restricts but not fully obstructs air flow through the unit between said conduits, a thermally responsive device disposed in a position in which it is directly and immediately responsive to the temperature of the air delivered by said hot air conduit and operable to control said dampers and cause the operationv of .both dampers into flow restricting positions whenever the temperature of the air delivered by said unit falls belowa selected temperature above normal room temperature, and means for keeping said motor operated blower continuously running when the temperature of the air delivered by the hot airconduit is above a desired temperature that is below said selected temperature.-

5. An improved heating system of the type in which heated air is circulated through an en- 1 closure, and comprising a heating unit, a cold a position in which it partially restricts but not completely obstructs flow of air through said stricting position whenever the temperature of the air delivered by the unit falls below a selected temperature but above normal room temperature, progressively as said air temperature falls,

, whereby air will be continually moving through said unit and between said conduits sufliciently to prevent objectionable drafts of relatively cool air and Stratification of the air in a room or rooms heated by said unit, andmeans for keeping said motor operated blower continuously running at constant speed whenever the temperature of the-air delivered by "said hot air conduit is above a desired temperature that selected temperature.

4. An improved heating system of the type in whichheated air is circulated through a room or is below said air supply conduit connected to one part of said unit, a hot air delivery conduit connected to another part of said unit, a motor operated blower associated with said unit and conduits for forcing air through the unit from said cold air conduit to said hot air conduit, said unit having heat exchanging means therein for heating air passing therethrough, means'for intermittently supplying heat to the heat exchanging means of said unit, a damper in one of said conduits operable' betweefi an open position in which it offers a minimum of resistance to air flow between the conduits through the unit and a restricting position in which it partially restricts but not fully obstructs dair flow through the unit between said conduits, thermally responsive device disto control said damper and cause the operation of the latter into flow restricting position whenever the temperature above normal room temperature of the. air delivered by said u'nit falls below a selected temperature but above room temperature, and means for keepingsaid motor operated blower continuously running when the temperature of the air delivered by the hot air conduit is above a desired temperature that is below said selected temperature.

6. In an improved heating system, the combination of a cabinet, a cold air conduit opening into one part of said' cabinet, a hot air conduit opening into another part of said cabinet, a motor operated blower associated with saidcabinet and conduits and operable to forcibly circulate air through said cabinet from said cold air conduit to said hot air conduit, a heat exchanging device within said cabinet and having heat exchanging relation to air passing through the cabinet, means, for intermittently supplying heat to said exchanger, a damper in each ofsaid conduits and operable as a unit to restrictbut itemperature.

not fully obstruct the flow of air through said cabinet and conduits, a thermally responsive device disposed in a position in which it is directly and immediately responsive to the temperature of the air in said unit and delivered to said hot air conduit, means by which said thermally responsive device will cause the operation of said dampers into positions in which they partially restrict but do not fully obstruct the flow of air through said cabinet, whenever the temperature of the air delivered by said cabinet to said hot the air delivered by the hot air conduit is above a' desired temperature that is below said selected 7. In a heating system of the type in which heated air is circulated through a room or rooms and the heating unit, that improvement in a heating unit therefor which comprises a cabinet,

a cold air conduit opening into said cabinet atone zone thereof and by which air from said room or rooms may be conducted to said cabinet,

a hot air conduit opening from another zone to said cabinet and by which heated air may be delivered to said room or rooms, heat'exch'ange' meam within said cabinet, a m-otoroperated blower associated with said cabinet and conduits and operable to circulate air through said unit from said cold air conduit to said hot air conduit and in heat exchanging relation to said heat exchange means, means for intermittently supsupplying heat to said heat exchange device, means for continuously circulating air through said cabinet between said conduits whenever the temperature of the .air delivered by the hot air conduit is above a desired temperature, and

' means directly and immediately responsive to the plying heat to said heat exchange means, damper means disposed to directly control the passage of air through said cabinet between said conduits and selectively operable to offer a minimum of resistance to flow through said cabinet or to restrict but not fully prevent flow of air through said cabinet between said conduits, means directiy and it immediately responsive to the temperature of the air delivered by said unit to said hot air conduitfor controlling the operation of said damper means in a manner to restrict but not fully obstruct flow of air through said cabinet between said conduits. whenever the temperature of the air in said unit-and delivered to said hot air conduit falls below a selected temperature above normal room temperature, said damper operation being approximately proportional in degree to the change in temperature in interconnected for concomitant operation, and a- -thermally responsive device disposed in said hot ilk said delivered air, below a selected temperature improvement in the heating unit thereof which comprises a cold air conduit by which air may be withdrawn from the room or rooms and conducted to said unit. a hot air conduit by which hot air maybe. delivered to said room or rooms from said unit, a cabinet into diiierent zones 0! which said conduits open, 'a heat exchanging device, in said cabinet and in contact with air passing through the cabinet, means for intermittently temperature of air delivered by said unit to said hot air conduit for restricting but not fully obstructing the flow of air through said cabinet when the temperature of the air delivered by the cabinet falls below a selected temperature above normal room temperature and above said desired temperature and operable progressively in degrees of change within a selected range of temperatures.

9. An improved heating system of the type in which heated air is circulated through a room or rooms and a heating unit in succession, that improvement in the heating unit thereof which comprises a cold air conduit by which air may be withdrawn from the room or rooms and conducted to said unit, and a hot air conduit by which hot air may be delivered to said room or rooms from said unit, a cabinet into different zones oiwhich said conduits open, a heat exchanging device in said cabinet and in contact with air passing through the cabinet, means for intermittently supplying heat to said heat exchange device, means for continuousl circulating air through said cabinet between said conduits whenever the temperature of the air delivered by the hot air conduit is above a desired temperature, and means directly and immediately responsive to .the temperature of air delivered by said unit to said hot air conduit for restricting but not fully obstructing the flow of air through said cabinet when the temperature of the air delivered by the cabinet falls below aselected temperature above said desired temperature, said last named means including a damper disposed in said cold air conduit and another in said hot air conduit, said dampers being air conduit and operable upon said dampers to control their movements.

10. In an improved heating system of the type in which heated air is circulated through a room or rooms and a heating unit in succession, that improvement in the heating unit which comprises a .cold air conduit by which air may be withdrawn from a room or rooms and conducted to said unit, and a hot air conduit by which hot air may be delivered to said room or rooms from said unit, a cabinet having different zones into which said conduits open, heat exchange means in' said cabinet for heating the air passing through the cabinet, means for intermittently supplying heat to said heat exchange means, means for continuously circulating air through said cabinet between said conduits whenever the temperature of the air delivered from the cabinet exceeds a desired temperature, automatic means responsive to the temperature'of the air delivered by said unit to said hot air conduit for materially restricting but not fully obstructing the flow of air through said cabinet whenever the temperature of the air delivered by the cabinet falls below a selected temperature that is above saiddesired temperature, means for supplying moisture to the air passing through said cabinet at a zone before it reaches said heat exchange means, and means also controlled by said temperature responsive, means for rendering the moisture supplying means ineiiective whenever room temperature.

ing air through said cablnet'fromsaid cold air amen falls below a selected temperature, and discontinuing the forced circulation of such-air when conduit to said hot air conduit, means within said cabinet for heating the air passing therethrough, a damper in one of said conduits, means responsive to the temperature of the air delivered to said hot air conduit for causing operation of said damper from an open position to a position in which it materially restricts but does not fully obstruct flow of air through said cabinet, means for spraying moisture into the air passing through said cabinet before said air reaches said air'heating means, an electrically operated valve controlling the supply of moisture to said spraying means, and means including a switch operable .by said temperature responsive-means simultaneously with the operation of said damper into flow restricting position, for causing an op- -eration of said valve to cut off the moisture supplied to said spraying means whenever the damper is operated into flow restricting position and re-establishing the supply of moisture to said spraying means automatically whenever the v damper is operated to open position.

12. In an improved heating system of the type circulated in heat exchanging relation to a heat exchange element and then returned to the room or rooms, and in which a heating medium is supplied to the heat exchange element in variable amounts in accordance with the temperature requirements of the air in the room,'the improved.

method which comprises forcibly circulating the air from the room or rooms through said heat exchanging relation with said heat exchange element, partially restricting, but not fully obstructing, said circulation of air through said heat exchanging relation whenever the temperature of the air circulated past and leaving said heat 'exchange element falls below a selected temperature well above normal room temperature while continuing the circulation of air, and discontinuing 'the'forced circulation of the air whenever the temperature of the circulated airleaving the heat exchange element falls below a still lower selected temperatur which is above normal 13. In an improved heatirig system of the type the temperature falls below a still lower temperature, but still above normal room temperature,

automatically in response to. such further fall of temperature.

14. An improved heating system of the type in which heated air iscirculated through a room or rooms, and comprising a heating unit. a cold air supply conduit connected to one part of said unit, a hot air delivery conduit connected to another part of said unit, a continuously operating but not fully obstructs air flow through the unit between said conduits, a thermally responsive device disposed in a position in which it is directly and immediately responsive to the temin which air is withdrawn from a room or rooms,-

perature of the air delivered by said hot air conduit and operable to control said damper and cause the operation of the latter into flow restricting position whenever the temperature of the air delivered by said unit falls below a selected temperature above normal room temperature,

' and automatic means also controlled by said in which air is withdrawn from a room or rooms to be heated, circulated in heat exchanging relation with an intermittent source of heat and returned to the room or rooms to be heated, the improved method which comprises withdrawing air from a roomor rooms to be heated, fofcibly circulating itcontinuously in "heat exchanging relation to an intermittent source of heat, and then returningit to the-room or rooms from which it was withdrawn, supplying moisture to said withdrawn air before it is subjected to said heat exchanging relation, discontinuing the supply of moisture to the air when the temperature of the air, immediately after the heat exchanging relation, falls below a selected temperature and automatically in response to such fall of temperature, mechanically restricting, but not fully obstructing, the forced circulation of 'air through said heat exchanging relation automatithermally responsive device for stopping operation of said blower whenever the temperature of air in said hot air conduit falls below a still lower selected temperature and for starting it whenever the temperature of air in said hot air conduitrises above said still lower temperature.

15. In an improved heating system of the type in which heated air is circulated through a heating unit and a room or rooms in succession, that improvement in the heating unit thereof which comprises a cold air conduit by which air may be withdrawn from a room or rooms and cdnducted to said unit, a hot air conduit by which hot air may be delivered to said roomor .iiooms from said unit, a cabinet into diiferent f0? circulating air through saidcabinet between said conduits, a damper in said cold air con'duit operable between open and closed positions, but a in its closed position largely obstructing but not fully preventing movement of air therepast, a

thermal device in said hot air conduit and causing operation of said damper into said closed position when the air temperature in the hot air conduit falls below a predetermined temperature above normal room temperature, and cans--v ing it to open when the temperature in the hot air conduit rises above said predetermined temperature, and means for preventing movement of said damper beyond open position when the temperature of the air in the 'hot air conduit rises above the temperature at which the damper is fully open but-within the normal temperature range of operation of said unit.

16. In an improved heating system of .the type in which heated air is circulated through a heating unit and a room or rooms in succession, that improvement in the heating unit thereof which comprises a cold air conduit by which are.may

be withdrawn from a room or rooms and conducted to said unit, a hot air conduit by which hot air may be delivered to said room or rooms a fully preventing movement of air therepast, a

thermal device in said hot air conduit and causing operation of said damper into said closed position when the air temperature in the hot air conduit falls below a predetermined temperature, and causing it to open when the temperature m the hot air conduit rises above said predetermined temperature, means for preventing movement of said damper beyond open position when the temperature of the air in the hot air conduit rises above the temperature at which the damper is fully open but within thenormal temperature range of operation of said unit, and

another damper in said hot air conduit approxi- 'mately at said thermal device and connected for its operation directly and make the thermal de-- vice directly responsive to even minor changes in the temperature of theair in said hot air conduit when said dampers are in closed positions.

17. In a domestic heating device, a cabinet having inlet and outlet connections by which air may be circulated therethrough, and to and from an enclosure to be heated, a heat exchange element in said cabinet for heat exchange with said air circulating through said cabinet, means for supplying heat .to said element in variable amounts, a motor operated blower for forcibly circulating said air through said cabinet and continuously operating whenever the temperan ture of the air leaving said cabinet is above a desired temperature, damper means for controlling the air flow through said cabinet and operable between an open, flow permitting condition and a condition in which it partially but not fully restricts said air flow, and thermally responsive means directly, immediately and automatically responsive to the temperature of said for supplying heat to said element in variable amounts, a motor operated blower for forcibly circulating said air through said cabinet and continuously operating whenever the temperature ofthe air leaving said cabinet is above a desired temperature, damper means in said inlet connection for controlling the air flow through said cabinet and operable between an open, flow permitting condition and a condition in which it partially but not fully restricts said air flow, and thermally responsive means directly, immediately and automatically responsive to the tom}; perature of said circulating air leaving saidhea t' exchange element for causing a movement o'f said damper means to said flow permitting con; dition whenever the temperature of said air leaving heat exchanging relation to said element exceeds a selected temperature well above ordinary room temperature and above said desired temperature, and for causing said damper means to move to said flow restricting condition automatically whenever the temperature of said air leaving said element falls below said selected temperature.

19. In a domestic heating device, a. cabinet having inlet and outlet connections by which air may be circulated therethrough, and to and from an enclosure to be heated, a heat exchange element in said cabinet for heat exchange with said air circulating through said cabinet, means for supplying heat to said-element in variable amounts, a motor operated blower for forcibly circulating said air through said cabinet and running continuously whenever the temperature of the air delivered from the cabinet exceeds a desired temperature, damper means in both of said inlet and outlet connections for controlling the air flow through said cabinet and operable between an open, flow permitting condition and a condition in which it partially but not fully restricta said air flow, ,and thermally responsive circulating air leaving said heat exchange element for causing a movement of said damper means to said flow permitting condition whenever the temperature of said air leaving heat exchanging relation to said element exceeds a selected temperature well above ordinary room temperature and above said desired temperature, and for causing saidda-mper means to move to said. flow restricting condition automatically whenever the temperature of said air leaving said element falls below said selected temperasaid aircirculating through said cabinet, means means directly, immediately and automatically responsive to the temperature of said circulating air leaving said heat exchange element for causing a movement of said damper means to saidflow permitting condition whenever the temperature of said air leaving heat exchanging relation to said element exceeds a selected temperature well above ordinary room temperature and above said desired temperature, and for causing said damper means to move to said flow restricting condition automatically whenever the temperature .0! said air leaving said element falls below' said selected temperature.

20. In a hot air heating system of the forced air circulation type in which air to be heated is taken into a heat exchange cabinet through each duct section secured to said shaft for movement therewith, one of said vanes having an opening therethrough from'face to face adjacent said shaft, and a thermally responsive mem ber disposed partially across said opening so as to be responsive'to the temperature of the air passing through and close to said opening and operable on said shaft and said vane with the op ing to shift said vanes simultaneously into and out of difierent positions regulating air flow through-said duct sections, the other of said vanes only partially restricting air flow through the duct section in which it is disposed when in straight across position in its related duct section.

21. In a hot air heating'system of the type in which air to be heated is taken into a heat exchange .cabinet through one duct and delivered from the cabinet through another duct, the improved automatic control for the flow of air through the cabinet which comprises a section of each of said ducts, a shaft extending across in which-air to be heated is circulated through both of said duct sections transversely thereof,

a damper vane in each duct section secured to said shaft for movement therewith, one of said vanes having an opening therethrough from face to face adjacent said shaft, a thermally respon- 'sive member disposed partially across said opening so as to be responsive to the temperature of the air passing through and close to said opening and operable on said shaft and said vane with the openingto shift said vanes simultaneously into and out of difierent positions regulating air flow through said duct sections by degrees depending upon temperature changes, the other of said vanes only partially restricting air flow through the duct section in which it is dis-, posed, when in straight across position in its related duct section, one end of said shaft extendin'g exteriorly of the adjacent duct-section, and electric switch means connected to and operable by said shaft at its said exterior end.

a heat exchange cabinet under the action'of a motor driven blower that is running continuously at uniform speed when the temperature of the air leaving said cabinet is abovea predetermined temperature, that improvement which comprises a cold air supply duct by which air to be'heated is delivered to said blower for redelivery to said cabinet, a hot air duct through which heated air is delivered from said cabinet, a flow controlling damper in each duct and when in flow restricting position causing a major, but

not complete, restriction in airflow through that duct, means connecting said dampers for corresponding simultaneous movements into and out of flow restricting positions, means directly responsive to the temperature of the air delivered by said hot air duct, substantially above said predetermined temperature, for automatically operating said dampers into and out of flow restricting positions through degrees of movement depending upon temperature changes, and with movement towards flow restricting position upon fall of temperature of the delivered air in the hot air duct, whereby noise will be minimized and power required for operating said blower will be a minimum when said dampers are posi tionedto restrict air flow through said cabinet.

CHARLES I, MURDOCK. 

